Theoretically speaking...
 

Theoretically speaking...

If one already has a well functioning XKR, and would like to explore the performance limits of this car, what is possible in terms of maximum HP & Torque, as well as weight reduction.

Let's assume a $70K to $80K budget in addition to a stock XKR.

Is 700 BHP & 570 lbs/ft achievable? And is it reasonable to reduce the total weight to ~3,100 lbs?

Would the end result be comparative / competitive with a 2017+ P-Car 991.2 GT2 RS on a race track?

Does anyone believe that this would make a worthy challenge?

Absolutely. Sell XKR, add proceeds to your budget and buy 700 BHP car.


Not unless you are willing to gut all interior, seats, AC and so on.

No, unless you go with my original suggestion of selling XKR.

You have sufficient budget to build yourself a decent race car. Unless you start with XKR. The insurmountable problems for you are - a) weight b) lack of aftermarket support. Instead, if you start with a Mustang or Corvette on your budget (including purchasing the car) you'd be well within your goal.

However, there is another wrinkle in this. The fact that you don't already know all of this tells me you are new to racing. Drive your XKR as-is (well, service brakes and better tires, like MP4S) and invest into driving school/lessons and more lap time. People race in Miatas and do well. It isn't about the car you drive, it is about how you drive it.

How and torque no issue handling a whole different ball game.

Is this strictly going to be a race car ???

In standard trim your looking at a 4000lb / 500hp vehicle

A few of the guys have done weight reduction ie lighter wheels , muffler delete , lighter brakes & lighter adjustable suspension .

All that would be good for a 200lb reduction , strip the interior and swap out some of the body work for carbon panels (definitely the roof to lower the centre of gravity ) and you might get closer to your goal .

In regards to 700hp that might be a long stretch but with increased boost , ecu tune , custom headers and high octane race fuel you would have to been in the mid to high 600s .


As ive always said the xk's tend to have a nose bias set-up 54/46 with clever weight reduction techniques you would have to rectify this issue to make it competitive ...difficult yes but very doable no doubt.

The car would be purpose built for the track.

It seems like most opinions are this is a poor car to do this with. What other cars would you suggest be used instead? (Keeping in mind a total budget of ~$90K to $100K to buy the car as well as modify it.) Using the same parameters of engine performance and weight guidelines.

C5 or C6 Corvette is the easiest path for that budget.

Is there a class you are trying to race in?

Track days for fun?

If you're looking to get serious with an XKR the XKR-S GT is a good starting point of what you'll need to do.

https://www.autocar.co.uk/car-review/jaguar/xkr-s-gt

A big question is are you just trying to make power/weight numbers that sound good, or are you planning to do time attack/racing?

Keeping with the British theme and something that would be a brilliant starting point transaxle and virtually perfect weight distribution would have to be the vantage .

The 4.7 wouldn't get you close to your desired power output of 700hp perhaps with a few tweaks you'd be knocking on the door of 500hp that brings me to the V12 power wise you'd be over 600hp and a in a chassis set up that makes more sense than the xkr

Mustang, Corvette, Subaru STI, Miata, BRZ. These cars have aftermarket support and it is possible to build a dedicated track car without incurring astronomical costs of custom engineering. Ultimately, you can turn anything into a competitive track car given unlimited budget. If I ever make it big I would turn a Prius into race car just to mess with people.

Personally, I find that buying existing track car and modding it to work for your driving style is even cheaper. Also, it is likely you will crash your first track car, so I wouldn't go with anything overly expensive.

See list above. Stay away from Porsche or double your budget. Personally, I think Mustang GT350 is a fantastic starting point for a track car.

I was thinking that, but I am unsure the costs would remain.

A GT3 Aston new is what, $200K? Even more than a GT3 Porsche.

Now if you wanted to stay British Engineering, Radical comes to mind.

Their custom made engine block and crank bringing together two hayabusa inline 4's into an incredible high revving V8 is a potent track day weapon.

A Radical with this engine isn't going to meet his power requirements, but it will be vastly under the weight requirement.

The base problem is the XKR wasn't designed with competing with a modern GT2 in mind.

You could find places to sacrifice comfort and style for less weight, and you could find more power.

But then you have a car that has lost what the XKR is, and there will still be other cars that do the go fast part better.

Looks like American Muscle would be the best starting point. Aston Martin is too high price a car to start with.

Perhaps an Ariel Atom would make a good starting point. One like this for under $50K could then be modified for additional power. The low weight is already there too!

https://bringatrailer.com/listing/20...tom-3-aa30124/

https://cdn.bringatrailer.com/wp-con...16-940x629.jpg

A late model 2016 Dodge Viper is 650hp standard and lighter and much better handling than any model XK which is an over steering pig.It can be lightened and tuned easily

The problem with this is a late model Viper starts at $100K!

This car is for sale in Florida.

Isnt it a bit perverse to try and convert a luxury grand tourer to a flying go-cart.
That would be like marrying Dolly Parton and wanting to convert her to Hussein Bolt.
I can see why someone with a Miata would want more power, or Bruce Jenner would want to become Dolly.

Wonder if this is still for sale....

https://www.jaguarforums.com/forum/x...2-sale-133729/

Also worth mentioning that Emil Frey have retired their XKR's from the European GT series end of last year... https://www.jaguarforums.com/forum/m...series-117341/

So perhaps one of them may be for up for sale?

These cars handle well. I don't think it's a huge leap to make them track worthy. Probably not $1M series worthy but...

Competitive with a 2017+ P-Car 991.2 GT2 RS on a race track is a giant leap from track worthy.

This is a car making a lap of the Nurburgring about a minute faster than a Jaguar XKR-S GT.

For track worthy all you really need is safety equipment, perhaps additional brake cooling.

Depending on what your tire temperatures do and how long your sessions are wider tires perhaps.

To top the GT2 RS is going to take downforce and balance in addition to power/weight.

I also have to say, normal drivers will have a tough time replicating what the Stability management does in the Porsche.

The Jaguar lacks this element.

Whatever ego may say, I see the results for most drivers.

Less mistakes, closer to the threshold, faster lap times.

The British built and engineered Radical may have less power, but it is deity mode downforce, the threshold is much much higher.

You could get a Radical SR8 in that budget, there would be precious little you would meet in a track day that would beat it, drivers being equal.

You won't be setting the trap speed records at the end of the straights, but the corner speed will more than make up for it.

Perhaps you don't know Dolly the way I know Dolly...